proc: move AllGCache to a common struct

Add a new method "Common" to proc.Process that returns a pointer to a
struct that pkg/proc can use to store its things, independently of the
backend.

This is used here to replace the AllGCache typecasts, it will also be
used to store the return values of the stepout breakpoint and the state
for injected function calls.

pkg/proc/core/core.go

@@ -147,7 +147,7 @@ type Process struct {
 	breakpoints       proc.BreakpointMap
 	currentThread     *Thread
 	selectedGoroutine *proc.G
-	allGCache         []*proc.G
+	common            proc.CommonProcess
 }
 
 type Thread struct {
@@ -298,8 +298,8 @@ func (p *Process) Exited() bool {
 	return false
 }
 
-func (p *Process) AllGCache() *[]*proc.G {
-	return &p.allGCache
+func (p *Process) Common() *proc.CommonProcess {
+	return &p.common
 }
 
 func (p *Process) Pid() int {

pkg/proc/gdbserial/gdbserver.go

@@ -121,7 +121,7 @@ type Process struct {
 	process  *os.Process
 	waitChan chan *os.ProcessState
 
-	allGCache []*proc.G
+	common proc.CommonProcess
 }
 
 // Thread is a thread.
@@ -584,8 +584,8 @@ func (p *Process) CurrentThread() proc.Thread {
 	return p.currentThread
 }
 
-func (p *Process) AllGCache() *[]*proc.G {
-	return &p.allGCache
+func (p *Process) Common() *proc.CommonProcess {
+	return &p.common
 }
 
 func (p *Process) SelectedGoroutine() *proc.G {
@@ -615,7 +615,7 @@ func (p *Process) ContinueOnce() (proc.Thread, error) {
 		}
 	}
 
-	p.allGCache = nil
+	p.common.ClearAllGCache()
 	for _, th := range p.threads {
 		th.clearBreakpointState()
 	}
@@ -710,7 +710,7 @@ func (p *Process) StepInstruction() error {
 		}
 		thread = p.selectedGoroutine.Thread.(*Thread)
 	}
-	p.allGCache = nil
+	p.common.ClearAllGCache()
 	if p.exited {
 		return &proc.ProcessExitedError{Pid: p.conn.pid}
 	}
@@ -819,7 +819,7 @@ func (p *Process) Restart(pos string) error {
 
 	p.exited = false
 
-	p.allGCache = nil
+	p.common.ClearAllGCache()
 	for _, th := range p.threads {
 		th.clearBreakpointState()
 	}

pkg/proc/interface.go

@@ -62,6 +62,8 @@ type Info interface {
 	ResumeNotify(chan<- struct{})
 	Exited() bool
 	BinInfo() *BinaryInfo
+	// Common returns a struct with fields common to all backends
+	Common() *CommonProcess
 
 	ThreadInfo
 	GoroutineInfo
@@ -100,3 +102,11 @@ type BreakpointManipulation interface {
 	ClearBreakpoint(addr uint64) (*Breakpoint, error)
 	ClearInternalBreakpoints() error
 }
+
+type CommonProcess struct {
+	allGCache []*G
+}
+
+func (p *CommonProcess) ClearAllGCache() {
+	p.allGCache = nil
+}

pkg/proc/native/proc.go

@@ -29,7 +29,7 @@ type Process struct {
 	// Normally selectedGoroutine is currentThread.GetG, it will not be only if SwitchGoroutine is called with a goroutine that isn't attached to a thread
 	selectedGoroutine *proc.G
 
-	allGCache           []*proc.G
+	common              proc.CommonProcess
 	os                  *OSProcessDetails
 	firstStart          bool
 	stopMu              sync.Mutex
@@ -230,7 +230,7 @@ func (dbp *Process) ContinueOnce() (proc.Thread, error) {
 		return nil, err
 	}
 
-	dbp.allGCache = nil
+	dbp.common.ClearAllGCache()
 	for _, th := range dbp.threads {
 		th.CurrentBreakpoint.Clear()
 	}
@@ -266,7 +266,7 @@ func (dbp *Process) StepInstruction() (err error) {
 		}
 		thread = dbp.selectedGoroutine.Thread.(*Thread)
 	}
-	dbp.allGCache = nil
+	dbp.common.ClearAllGCache()
 	if dbp.exited {
 		return &proc.ProcessExitedError{Pid: dbp.Pid()}
 	}
@@ -397,6 +397,6 @@ func (dbp *Process) writeSoftwareBreakpoint(thread *Thread, addr uint64) error {
 	return err
 }
 
-func (dbp *Process) AllGCache() *[]*proc.G {
-	return &dbp.allGCache
+func (dbp *Process) Common() *proc.CommonProcess {
+	return &dbp.common
 }

pkg/proc/proc.go

@@ -373,22 +373,14 @@ func StepOut(dbp Process) error {
 	return Continue(dbp)
 }
 
-// If the argument of GoroutinesInfo implements AllGCache GoroutinesInfo
-// will use the pointer returned by AllGCache as a cache.
-type AllGCache interface {
-	AllGCache() *[]*G
-}
-
 // GoroutinesInfo returns an array of G structures representing the information
 // Delve cares about from the internal runtime G structure.
 func GoroutinesInfo(dbp Process) ([]*G, error) {
 	if dbp.Exited() {
 		return nil, &ProcessExitedError{Pid: dbp.Pid()}
 	}
-	if dbp, ok := dbp.(AllGCache); ok {
-		if allGCache := dbp.AllGCache(); *allGCache != nil {
-			return *allGCache, nil
-		}
+	if dbp.Common().allGCache != nil {
+		return dbp.Common().allGCache, nil
 	}
 
 	var (
@@ -458,10 +450,7 @@ func GoroutinesInfo(dbp Process) ([]*G, error) {
 			allg = append(allg, g)
 		}
 	}
-	if dbp, ok := dbp.(AllGCache); ok {
-		allGCache := dbp.AllGCache()
-		*allGCache = allg
-	}
+	dbp.Common().allGCache = allg
 
 	return allg, nil
 }

pkg/proc/proc_test.go

@@ -1515,10 +1515,7 @@ func BenchmarkGoroutinesInfo(b *testing.B) {
 	withTestProcess("testvariables2", b, func(p proc.Process, fixture protest.Fixture) {
 		assertNoError(proc.Continue(p), b, "Continue()")
 		for i := 0; i < b.N; i++ {
-			if p, ok := p.(proc.AllGCache); ok {
-				allgcache := p.AllGCache()
-				*allgcache = nil
-			}
+			p.Common().ClearAllGCache()
 			_, err := proc.GoroutinesInfo(p)
 			assertNoError(err, b, "GoroutinesInfo")
 		}